Clamps are used in many areas for interconnecting structural members in the mechanical assembly of components. Clamps may be used in the positioning of light fixtures, on laboratory equipment and on scaffolding and shoring frames used in construction, to name only a few. With particular reference to the construction field, several arrangements of clamps have been developed over time which are particularly suited for clamping tubes and the like to shoring and scaffolding frames in assembling the framework so as to support the frames in forming columns and the like. Normally such clamps are designed to clamp one circular tube to another circular tube where the clamps are fixedly secured to one another. This is usually accomplished by having common clamp jaws integrally formed. Examples of such clamps are disclosed in U.S. Pat. No. 1,706,214 and U.S. Pat. No. 2,194,883. These patents are representative of scaffolding clamps which are fixed to clamp one tubular member at 90 degrees or at 45 degrees relative to the other tubular member.
There are however situations where in clamping one structural member to another their angular relationship may not always be that defined by a particular fixed clamp arrangement. Thus swivel interconnections having unrestricted relative rotation between the clamps were devised to accommodate variations in angular relationships between the members to be clamped. The difficulty with a swivel-type clamp is that in not fixing the relative positions of the members, the assembled structure may permit some movement and is therefore somewhat weaker for supporting loads. Examples of swivel-type clamps are disclosed in U.S. Pat. No. 2,945,713, Australian Pat. No. 152,133 and Canadian Pat. No. 369,685. The Australian Patent discloses that the swivel connection can be fixed by simply welding the components together to provide the fixed arrangement. Also in Canadian Pat. No. 369,685 alternative configurations are shown for fixed interconnections which is similar to that disclosed in U.S. Pat. No. 1,706,214.
Attempts have been made to provide a type of clamp arrangement which has the advantages of swivelling between the clamps and provision for fixing the relative positions for the clamps. Examples of such clamps are disclosed in U.S. Pat. No. 1,706,215 and Canadian Pat. No. 356,357. The clamp arrangement of U.S. Pat. No. 1,706,215 may be swivelled to a desired position with the ratchet teeth separated and then upon meshing the teeth and tightening a bolt to secure the meshed ratchet teeth, a desired fixed positioning of the clamps is achieved. With Canadian Pat. No. 356,357 the clamps may swivel relative to one another through a distance predetermined by the arcuate slot in one clamp body portion. Upon tightening of the bolt the clamps are fixed in a desired position. In this arrangement the distribution of loads for the device in fixing the clamps' positions is offset from the central axis about which the clamps can rotate. This unequal distribution of the loads does not provide for a secure clamp interfit and can result in failure of the clamps when placed under load. Secondly, the clamp does not offer a full swivel of the interconnected clamps without restriction.
With the ratchet tooth arrangement of U.S. Pat. No. 1,706,215, the teeth are separated to provide for relative rotation between the clamps. The interconnection for the clamps has not, however, been adapted in any way to maintain separation between the teeth for rotation. Instead the interconnection is such that the teeth of the ratchet arrangement are meshed when the clamp is in use. To withstand the loads which may be exerted on the clamp, the teeth should be constructed of a harder metal, such as steel. Thus care in design must be exercised when the arrangement is made of less hardenable metals.
The clamp arrangement according to this invention overcomes the above problems in providing an interconnection for clamps which is adapted to give either rotation between the clamps or positioning of the clamps in at least one predetermined fixed relative position.